1991 Chevy Blazer Runs Hot - Intermittantly

KLEMPELDT

MEMBER
1991 CHEVROLET BLAZER
V8
4WD
MANUAL
235,000 MILES

I recently had the engine in my Blazer (5.7L TBI) rebuilt. I initially had some trouble getting it running smoothly, but eventually working with my mechanic, got it running well. HOWEVER, engine seems to run pretty hot (around 210 F) about 50% of the time. The other 50% it runs around 185 F. When it is running hot, there is a noticeable lack of power & it smells prett "exhausty" and rich. I have done the following:

Flushed Radiator
Installed new thermostat
Replaced BOTH temperture sensors (one for guage, one for ECM)

4 Replies

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

210 really isn't that bad. Make sure the timing is accurate and the distributor isn't lose. Let me know what you find.

Also, when it runs hotter, does it happen at any specific time (in traffic)?

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Wednesday, September 2nd, 2009 AT 9:47 AM

KLEMPELDT

MEMBER
3 POSTS

I will check the timing, although I don't think that is it becasue it is only an intermittent problem - half the time it runs perfectly. To me it seems like it is a bad sensor, or the ECM is getting bad data and reverting to some baseline settings.

The temperature at 210 by itself doesn't bother me, just that it doesn't seem to run as well in general when the temperature is hotter. I think the 210 temp is a symptom of something else, and isn't the cause of the problem.

It doesn't seem to matter what kind of driving I am doing - sometimes it runs at 210 and sometimes it runs at 185, with no reason. For instance this weekend I went hunting and went over McDonnel pass in the morning and it was running hot and not running very well. When I came back over the pass later that day, it was running well, and I went over the pass at 65 mph wit hno problems.

I'll get back to you on the timing. Thanks.

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Friday, September 11th, 2009 AT 6:22 PM

JACOBANDNICKOLAS